Balance testing device



April 28, 1953 s. w. MARTIN 2,636,382

BALANCE TESTING DEVICE Filed Feb. 14, 1950 3 Sheets-Sheet 1 I I I n I i INVENTOR.

April 28, 1953 s. w. MARTIN BALANCE TESTING DEVICE 3 Sheets-Sheet 2 Filed Feb. 14, 1950 k 5 y l w W W 71w W9 7 .1 @MM 1 m j q.

f wmv W 5 m April 1953 s. w. MARTIN 2,636,382

BALANCE TESTING DEVICE Filed Feb. 14, 1950 3 Sheets-Sheet 3 Patented Apr. 28, 1953 BALANCE TESTING DEVICE Sidney W. Martin, Chicago, Ill., assignor to Bear Manufacturing Company, Rock-Island, 111., a corporation of Delaware Application February 14, 1950, Serial No. 144,110

12 Claims.

The present invention relates to apparatus for determining and evaluating conditions of unbalance in rotatable bodies.

A primary object of the invention is to provide improved and simplified means for quickly and tatable body.

wheel or rotating body.

cabinet of relatively small size.

present disclosure in its entirety.

In the drawings:

tion;

trical indicating means; and

designated II, I2, and also serve as transverse bracing elements. The motor is mounted with its armature shaft vertical. A pulley I I is fast upon the armature shaft and a belt I 9 provides driving connection between the motor and a pulley 23 through The wheel is tested with tire in place The bearing bushings 28, 29 are Section 41 constitutes the upper ex- An axially positioned Stem i] and ball 52 are locked to The internal diameter of the quill 89 is 5 the agency of which a vertical shaft structure, Conveniently d ng the location and the subsequently to be described in greater detail and amount of unbalance, both static and dynamic, which projects through the top Wall 22 0f the which may exist in a vehicle wheel or other rocabinet, is rotatable to enable powered rotation of the wheel during the checking of dynamic un- Another important object of the invention is 10 balance. to provide an improved balance-checking device thereon, and is adapted to be supported by the of the indicated character which incorporates shaft structure above the cabinet in the position easily operable power driven means for rotating indicated at 24 in dotted lines in Fig. l. the wheel or other object during the gaging of The shaft structure includes a vertical spindle dynamic balance, a W i fu she eas y 25 carrying the pulley fast upon its lower end readable visible indication of the location and and projecting upwardly through an opening 21 extent of any unbalanced condition that may in the top wall 22 of the cabinet. The spindle is exist, the visible indicating means being of such rotatably supported in vertically spaced smooth character that it is visible at a distance from the bearing bushings 28, 29, carried by a fixed tubular 20 bearing supporting sleeve and body member 39 Still another object is to provide improved having an integral securing flange 32 underlying apparatus of the indicated character which is of the top wall of thecabinet and rigidly secured very simple, rugged and foolproof construction, thereto as by screws 33. In the area to which the adapted to be incorporated in a single, compact body 30 is thu secured, the cabinet wall is rein- 25 forced as by transverse stiffening and bracing Other objects and advantages of the invention members 34, 35. will become apparent upon consideration of the provided with integral thrust bearing flange portions as 31, 39, overlying the ends of the supporting body 30, and directly above the top thrust Figure 1 is a perspective view of a balance bearing flange 31, a collar MI is secured to the gaging structure for motor vehicle wheels, conshaft as by means of setscrew 42. It will be noted structed in accordance with the present inventhat these portions are located above the top wall of the cabinet. Fig. 2 is a side elevational view thereof upon a Above the collar 40, the shaft is provided with larger scale and partly broken away; a reduced upwardly extending portion it having 3 is a top plan V w thereof; a keyvvay 45 extending longitudinally thereof, and Fig. 4 is a vertical sectional detail of the wheel above portion 44 the shaft is still further re- S pp S ur and indicatfil' actuating duced, such further reduced portion being desigmechanism, upon a still larger scale; nated 41.

Fig 5 s a ve t c se on l v ew, 1110 a still tremity of the shaft and is provided with a rel er scale, of the switching means for the elec- 40 entrant axially drilled hole 49, in which is fitted a stem portion 56 having at its top an integral Fig. 6 is a schematic diagram. h de d t el ball 52. Referring n w to the d aW gS,Wherein the in concave conical seat 54 is formed in the top of vention is shown incorporated in a device espethe ball 52. cially adapted for determining conditions of unthe shaft 25 by a transverse keying pin 55, and balance in motor vehicle wheels, a cabinet struc a pin 57 also extends substantially diametrical y ture is provided which may be of generally recand horizontally through the ball 52 and projects tangular form and economically constructed of from both sides of the ball. sheet metal. The cabinet structure is generally A tubular limitedly rockable driven spindle ele- II). In the preferred construction ment or quill 60 is removably supported. by the shown, the cabinet is internally braced by upright ball 52. angle iron members I I, I2 which serve to support greater than the external diameter of the portion an electric motor I l carried by metallic straps 4"! of the shaft 25 and extends downwardly there- I5, I5, which join and are secured to the uprights overto a position near the upper extremity of 5,5 the shaft portion 44.

The quill 6!] is adapted to serve as a support for a motor vehicle wheel to be tested, the wheel when supported thereupon being held in such manner that its geometric axis coincides with the axis or the quill. A generally conical abutment or rest 62 is carried by the quill 68 near the bottom, beim held against slipping oi the bottom of the quill by a snap-ty e lock ring 66 and an annular skirt ring 65. The rest cone E2 tapers toward a minimum diameter at the top and is slidable on the quill. so that it may be removed to permit the substitution of rests of different proportions, and/or to allow the placement of a s acer bet een the underside of the cone and the ring 85, if desired. A oomplementaryinverted clamp ng cone E56 is slidably fitted upon the quill above the cone t2. and is movable toward the bottom cone 52 under pressure adapted to be exerted upon the top of the up er cone by a clamping hand nut til fitted u on screw threads 69 formed upon the u per end of the quill. Nut 6'! is removable from the uill to permit removal and re lacement of the wheel-holding cones E2, 66.

The means for supporting the uill u on the shaft is entirely housed within the hollow interior oi the quill, and is so arranged that during static balancing, the quill is adapted to be supported by engagement between the pointed lower extremity of an axially positioned static balance supporting pin ill, carried by the quill,

and the conical seat 56 formed in the top of the ball 52. When the uill issupported in this mannor, there is no driving engagement between the shaft and the quill, and the quill (and wheel supported thereby) are freely rookable in all directions. During dynamic balancing, the quill and. wheel are supported by a socket bearing block :72, also mounted in the quill and having a spherical seat it at its lower end which at that time rests upon the spherical surface of the ball 52. The lower end of the socket block "(2 is transversely slotted as indicated at 75, such slots being proportioned to fit over the projecting ends of the drive pin El, so that the block 12, quill, and wheel are rotatable by the shaft. The transverse slotted portions i5 extend substantially above and below the pin 5?, so that the block and quill are rockable in all directions, as freely in the vertical plane which contains the pin 5? as in the erpendicular direction corresponding to rotation about the axis of the pin 5?.

The axial internal opening in the quill is of maximum diameter from the open lower end .iereoi" to a plane just above the socket block '12, where the diameter of the internal opening is reduced to define a shoulder T! which positions the block against upward displacement. The pin it is slidable in an axial hole 29 in the block. Near its upper end theaxial hole 19 is somewhat enlarged and tapped to provide an internally threaded nut portion 85! into whiohthe upper end of the stem ill projects. An axially positioned screw 932 is threaded at its lower end and fitted into the threads in the nut portion 80 and is held in substantially axial position within the quill by a spacing and stop collar 8 surrounding and pinned or otherwise secured to the screw. Near its upper end, which lies within and is spaced below the top of the quill, the screw carries a transverse drive pin 85 extending laterally therefrom. The screw 82 is rotatable by means of a handwheel 8'. having an integral tubular stem portion 85 projectable into the top of the quill and diametrically slotted at its lower end as indicated at 89. The tubular stem portion is slidably fitted over the upper end of screw member 82 and the slotted portion 89 is dimensioned to overengage the drive pin 85. The handwheel overlies. the top of the quill when the stem is inserted in the manner shown in Fig. 4, and accidental displacement of the handwheel and stem is prevented by a friction snap ring 90, mounted upon and near the lower end of the stem and held a suitable groove in the exterior of the stem, but bearing frictions-11y outwardly against the interior of the quill. The spring ring 90 is slidable in the smooth cylindrical upper portion 92 of the hole in the quill, but the internal diameter or" the ring is too small to permit the pro ecting ends of the pin 85 to pass through it, so that when the screw 82 is completely released from the nut portion till of the block 12, the screw may be removed with the handwheel 8i and stem 8% simply by lifting up on the handwheel and pulling it out of the top of the quill,

the ring 85 serving to pull out the screw 82.

In axial position on top of the handwheel 81 is a universal-type spirit level or inclinometer assembly so which may comprise a substantially cyl ndrical fluid-tight casing having a circular top window of upwardly convexed form and containing in the usual manner an air bubble floating in the liquid therein.

When the scr w 82 is backed on suilicien-tly, for example, as shown in Fig. 4, the load represented by the quill and a wheel carried thereby is transmitted through the shoulder ll and block l t to the spherical top surface or the ball 52 and at such time the will and wheel are drivable from the shaft 25 throu h-pin 55, stem 58, pin 5"; and block E2 to the quill. The block 12 is fast in the quill. As previously noted, the wheel under test and the quill are universally rockable during such rotation, by virtue of the universal joint furnished by the ball and socket portions 52 and Hi.

When the screw 82 is forced into the nut portion 855, in response to rotation of the handwheel P37 while the wheel under test and the quill are held against rotation, the nut portion and socket block l2 are lifted upon the pin l0, raising the entire quill and wheel, and suchaction may be continued until the slotted portion 75 is entirel free of the pin 5?. The socket portion id is then also free of the ball 52 and the entire quill and wheel assembly is supported by the pointed lower end of the pin in which then bears a ainst the conical seat 55 in the top of the ball. The wheel. and quill are then rockable withminimum friction, although no rotary drive can be im arted thereto.

Slid'ably keyed to the shaft portion M between the collar ll! and the'lower end of the skirt 65 is an indicator switch actuating mechanism responsive to dynamic unbalance. The indicator actuating assembly includes a sleeve 9'! slidably fitted. upon the shaft, but keyed against rotationwith respect thereto as by means of a keying portion 99 slidably projecting into the keyway 455. secured to-the lower end of the sleeve 8'. is an abutment and "bearing disk 108. Loosely fitted over the sleeve 9'! is an inverted cup-shaped housing portion I02, the exterior of which is substantially cylindrical. Housing :02 is smaller in diameter than the disk It!!! and the lower edge of the housing substantially abuts the disk I00, although the disk Hill and sleeve 9! are urged downwardly with respect to the cupped housing by the compression spring I M surrounding the sleeve within the housingand bearing downwardly against the disk and upwardly against the flat top wall I05 of the housing.

Mounted on the flat top wall I05 of the housing I02 in such manner as to be laterally slidable thereover, but frictionally held in any position of lateral adjustment to which it may be moved, is a ring I01 having an upwardly facing socket-like opening defined by a wall I09 of truncated conic form. The mean diameter of the wall I09 is preferably substantially equal to the outside diameter of the skirt 65, and the ring I 01 is adapted to be moved upwardly with the housing cup I02 until the wall I09 engages the circular outer lower corner of the skirt 65. It will be appreciated that in this manner, if the quill is tilted with respect to the shaft so that skirt 65 is not concentric with the axis of the shaft, the ring I01 will be shifted laterally to a conformable extent by camming action between the lower corner of the skirt 65 and the slo ing conic wall I 09 of the ring I01. The central opening H in the ring I01 is large enough to permit lateral shifting of the ring to the extent of the maximum possible tilted inclination of the quill. Contiguous with the bottom face of the ring I01 is a radially inwardly extending flange III of relatively thin fiat form, and the inner edge of which defines the opening IIO. A flat radially outwardly extending flange I I3 is rigidly carried by the upper end of the sleeve 91, and is shown formed integrally therewith. The spring I04 urges the top flange I05 of the cup I02 upwardly against the bottom of the flange I I I, and urges the sleeve flange I I3 downwardly against the to of flange III, so that the ring is frictionally held against lateral shifting movement, but since all of these parts are flat and smooth, the ring is laterally shiftable by the exertion of a predetermined force thereupon, and the force required to move the ring I01 in this fashion is uniform throughout its range of movement.

The dynamically shiftable ring I01 and the supporting structure therefor, just described, may be bodily shifted upwardly by means of a forked yoke II5, freely encircling the collar 40 below the disk I 00 and movable upwardly against the bottom of the disk to force the disk and the dynamic ring assembly upwardly. The yoke has a hub portion I I6 secured by a setscrew II1 to a vertically slidable rod II9 which projects downwardly through a fixed bearing su port I into the interior of the cabinet. Within the cabinet, the lower extremity of the rod H9 is articulated to the end of a lever I22 which extends longitudinally through the cabinet to a position near the opposite end thereof. Intermediate its ends, the lever I 22 is pivoted upon a pivot pin I24 carried by the upright II, and at its end opposite to the point of articulation to the rod II9 the lever is connected to a substantially vertical rod I25 which extends upwardly through the top wall of the cabinet and to a position spaced thereabove where it carries a handle ball I26. The yoke H5 is urged downwardly by a compression spring I21 which bears upwardly against that end of the lever I22 remote from rod II 9, the opposite end of said spring bearing upon a portion of the cabinet (not shown). The yoke II5 also carries a hook I rigidly secured thereto and extending upwardly to a position spacedly above the disk I00 and then radially inwardly so that it overlies the disk.

Carried by the top of the cabinet and posi- 6. tioned to be actuated by the ring I01 and to indicate the lateral displacement thereof is an electrical switching assembly, the body of which is generally designated I 35, and the details of construction of which are best shown in Fig. 5. The body I 35 of the switch is formed of insulating material and it is secured to the top of the cabinet as by screw means I31 serving to attach it to the upper surface of a clamping and positioning ring I39 surrounding the shaft and the tubular shaft supporting housing 30 above the cabinet. Ring I39 forms a complementary securing element for coaction with clamping flange 32, the screws 33 extending upwardly through flange 32 and through the bracing elements 35, 34, cabinet top panel 32, and into the ring I39. The bearing portion I20 for the rod II9 may also be formed as an integral extension of the ring I39 a shown in Fig. 4.

The switch body I35 carries a contact plunger I40. The plunger is horizontally slidable in the block-like body substantially in horizontal alignment with the position of the dynamically displaceable ring I01 when the latter is in its lowered position, the plunger projecting to a position to be actuatable by the ring. The plunger is of composite construction, consisting of a central stem or core portion formed of insulating material and to which the reference numeral I40 is applied, and a metallic tube element I42 encircling the core portion and secured thereto as by the pin I44, but stopping short of the outer extremity of the core. The projecting end of the plunger assembly is covered by a sheet metal strap element which serves as a camming device and also to protect the plunger. The strap element incorporates inclined top and bottom camming wall portions I45, I46 formed integrally with a substantially vertical supporting leaf portion I41 secured at its lower end to the wall of the casing I35 which faces the shaft assembly. The sloping wall I is so inclined as to assist in camming the plunger inwardly during downward movement of the dynamic cone ring I01 after lateral deflection of such ring under the influence of dynamic unbalance, as will be more fully explained.

The plunger assembly I40, I42 is lim tedly slidable in a metallic bearing tube I50 in the body I35. Tube I50 concentrically encircles the plunger assembly and is also slidable in the body I35 and extends transversely across a vertically intersecting slot I52 in the body. To the right of the slot I52, as the parts are viewed in Fig. 5, the sleeve I50 is provided with an inwardly extending flange I54 which is also located spacedly to the right of the plunger portions I 40, I 42. A relatively long adjusting screw I55 is axially threaded in a tapped hole in the rear end of the insulating plunger core portion I40 and extends from the right end of the body I 35. An insulating bushing I51 surrounds the portion of the screw I55 which projects through the flange I54. Mounted upon the screw at the right end of the bus ing I 51 is an abutment washer I50 and behind the abutment washer is a compression spring I arranged upon the screw and reacting to the left against the Washer and to the right against a retainer cup I62 fast in the body I35. The insulating core portion I40 projects to the right slightly beyond its surrounding sleeve portion I42. Secured to the screw between the core portion I 40 and the flange I54 is a metallic contact collar I6I which is shorter in an axial direction than the space between the rower than the slot in a direction parallel tothe axis of the'plunger, so that the armis'movable with axial displacement of the :sleeve ii 5.8. A combined electrical terminal and setscrew it? provides for electrical connection to "the metallic retainer cup .562 and locks the latter in place. The arm I65 and sleeve 150 are urged to the left as the parts are viewed in Fig, 5 by a springpressed plunger its. When moved to the right, the arm I65, which constitutes a switch contact arm, is adapted to successively engage a plurality of plungers, arranged in spaced superposed relation in the switch body and slidably projectable in horizontal paths into the slot 152, although mounted in such manner that they project into such slot for limited distances only and to varying extent. The top plunger, designated ii I, projects farthest into the slot, plunger I72, next therebeneath, projects into the slot a lesser distance, and the lowermost plunger H3 projects into the slot for the shortest distance. plungers are formed of suitable conductive material such as carbon, and each is slidable in a metallic tube as H 5, H5, H5, externally threaded and fitted into a conformably threaded opening in the body. The plungers are urged into i the slot by compression springs as ill arranged behind each plunger, and each spring is in turn retained by a plug H9 fitted in the rear end of the plunger sleeve. Electrical connection to each of the plungers is adapted to be effected by means of terminal screws as 581, 582, 883, extending through the side of the body and adapted to serve both as terminal means and as set-- screws for locking the respective plunger sleeves H4, H5, lit in place. Electrical connection is also adapted to be made to the switch contact arm M5 by means of a flexible pigtail connector 185.

It will be notedthat the supporting structure for the wheel in the test, the electrical switching mechanism, and related components thus far described are located near one extremity of the cabinet, and that the actuating handle l26, previously referred to, is located near the other end of the cabinet. The last-"mentioned end of the cabinet, shown at the right in Figs. 2 and '3, constitutes the operators station and the design is such that all controls and indicating means may be located at this end of the cabinet. Secured to the top of the cabinet near the knob 2 5 is an indicator housing I99 within which are four electric light bulbs lei, H32, 23, I34, visible through appropriately positioned window openings '(undesignated) formed in the top of the housing 598. The bulbs are mounted in individual lamp sockets as I95. One terminal of each of the lamp sockets is connected to a conductor lei. The other terminal of the socket for lamp I9! is connected by a conductor 99 to the terminal. 8! for plunger ill, The other terminal of the socket for lamp I92 is connected by a conductor 2% to the terminal I82 for the plunger H2, and the other terminal of the socket for lamp its is connected by a conductor 202 to the terminal 83 for the plunger H3. The other terminal of the socket for lamp E95 is connected by a conductor 284 to the terminal ltl, which is connected to the retainercu 162 for the plunger assembly M0, M2. The con- The the foregoing.

ductor 185, comprising the pigtail connector I85 previously mentioned, is connected by means of a conductor 205 to the other voltage supply line. The voltage supply may comprise .the conventional .110 volt commercial supply or any other suitable current source. As also shown in Fig. 5., the motor 14 may :be operable .upon the same current supply. The motor is of a variable speed-type and is shown as connected through a conventional double pole, single throw switch" 201 to the current source, one terminal of the motor being connected in series with a hired resistor 2G9 and an adjustable resistor 2H). A part of the adjustable resistor is adapted to be shortcircuited by a single pole, single throw switch 212 which is'biased by spring means, not shown, to the-open position, but which is adapted to be closed to short-circuit the resistance and increase the voltage fed into the motor for short periods to increase its torque to assist rapid acceleration.

To enable stopping a wheel under test rapidly, a brake mechanism is incorporated comprising a brake shoe 2H5 adapted to frictionally engage the fiat bottom surface of the pulley 28. The brake shoe is carried by a lever arm 2i? secured to a rockshaft 2H? actuatable by another lever arm 2252 which extends to the control position previously mentioned at the opposite end of the cabinet, where it is articulated to a vertically slidable rod 222, which projects upwardly through and above the top of the cabinet carrying at its top a handle ball 22 1. The handle end of lever 22B is urged upwardly by a tension spring 225 reacting upwardly upon such end of the lever and thereby urging the brake shoe out of engagement with the bottom braking surface of the pulley '29. It will be seen that by bearing down upon the handle ball 225, the shoe may be forced into engagement with the pulley to arrest rotation of the shaft 25, and thereby of a wheel under test.

It is believed that the operation of the device during static balance testing will be obvious from stalled by first removing handwheel 87 and the connected parts, and by also removing the hand nut 61 and the top cone 56, placing the wheel upon the bottom cone t2 reapplying the top cone 5t and hand nut 67 and tightening the latter. The hand'wheel ill and screw 82 are then reinserted and the handwheel is turned to the right as far as possible to lift the socket block 2 and the entire quill and supported wheel under test until the entire quill and wheel supporting assembly is carried only by the pin It resting in the socket 5d. The inclinometer assembly as will then indicate static unbalance, which can be corrected in the usual manner by applying suitable weights to the wheel, as by attaching them to the rim. If there is substantial static unbalance, I prefer to apply half the required weight to each side of the rim, to avoid the introduction of dynamic unbalance.

After static balance is corrected so that the bubble is centered in the inclinometer glass, the handwheel is turned in the opposite direction to back-on the screw 52 and to allow the quill and. socket block to move downwardly, until the socket 7 4 in the block is seated on the spherical surface of the ball and the pin It is free of the seat 54. The pin is preferably formed integrally with the screw 32, and the pin, screw and handwhee'l assembly'maybe completely removed and placed to The wheel to be tested is in one side during the subsequent dynamic balance checking operations.

To check dynamic balance, the motor switch 201 is turned on and the wheel brought up to speed. Any dynamic unbalance existing will manifest itself in a tilting of the wheel and quill about some transverse axis which extends through the center of the ball 52 and which rotates with the wheel.

This will cause the'skirt 65 to move in an orbit. The radius of the orbit is a measure of the extent of dynamic unbalance, and the position of the axis of tilt with respect to the shaft and wheel furnishes an indication as to the location of the dynamic unbalance.

With the wheel rotating in the tilted condition so, that it appears to wobble, the handle knob I26 is pressed downwardly to force the carrier I02 and the dynamically shiftable cone ring I01 upwardly until the conical face E09 of the latter engages the bottom of the skirt 65. The ring I61 is, as previously noted, rotating at the same speed as the wheel and ring 65, but the offset position of the skirt due to the dynamic unbalance exerts a camrning action on surface I09 to shift the ring I01 to a correspondingly offset position. It will be noted that when the carrier I62 is moved upwardly in the described manner, the upward force exerted by the yoke II upon the disk I66 tends to move the flange II3 upwardly away from the flange III of the shiftable ring I61, so that the ring is readily shiftable by the skirt. When the knob I26 is released, however, to allow the carrier and shiftable ring to descend, the spring I04 becomes fully effective to cause the flange I I3 to grip the ring flange II I. Also during such downward movement of the carrier, the hook I36 may engage the top of disk I60 to "pull the bushing 91 downwardly, thereby increasing the gripping effect as the laterally deflected and rotating ring I01 is pulled downwardly over the sloping surface I45 of the plunger actuating leaf member I41. Thereafter, during continued rotation of the wheel and shaft, the ring I61 describes an eccentric path and actuates the plunger I46 inwardly once during each revolution.

During the initial part of each inward movement of the plunger, the contact collar l6I is moved into engagement with the flange I54 to complete a circuit through the conductor 204 to the locating lamp I94. If the extent of dynamic unbalance is sunicient to cause the arm I65 to move into engagement with one or more of the plungers I1I, I12, I13, the lamp or lamps connected to the plunger or plungers so engaged will also be intermittently illuminated. By reason of the fact that the plungers I1 I, I12, I13 are formed of carbon, the current transmitted therethrough, and consequently the brightness of illumination of the lamp connected to each plunger, varies in proportion to the pressure between the arm I65 and the plunger, in each case, in a readily observable manner. Thus, if the dynamic unbalance is of such degree as to cause the arm I65 to depress the plunger HI and to engage the plunger I12 with relatively light pressure, the locating lamp I9I connected to plunger I1I will be illuminated at full brillance, but the locating lamp I92 will be illuminated at reduced intensity. The parts may be so calibrated that the full illumination of lamp I9I indicates dynamic unbalance of such order as to require the application of corrective weights of approximately one ounce each at diametrically opposed positions and opposite faces of the rim of a motor vehicle wheel which is of approximately the usual dimensions, while full illumination of lamp I92 connected to plunger I12 indicates a need for two ounce correcting weights, and full illumination of lamp I93 connected to plunger I13 denotes unbalance requiring three ounce correcting weights. The switching mechanism causes the simultaneous illumination of all of the lamps up to and including the one denoting the highest weight required. Whenever more than one of the weight-indicating lamps ISI, I62, I93 is illuminated and the illuminated lamp corresponding to the highest weight is lighted with reduced intensity, however, the operator is able to determine that, for example, only one-half ounce of additional weight is indicated by the highest weight lamp so illuminated at reduced intensity.

After noting the amount of weight required to correct the unbalance in the manner indicated, the motor switch is opened and the wheel brought to rest, with the assistance of the brake mechablade I41 sufficiently to allow the plunger assembly to move to the left until the contact collar iEEI has moved slightly away from the flange Ifid. A mark is placed upon the tire at the point closest to the locating light I94 (which is positioned on the longitudinal center line Zeal of the top Ol the cabinet). The mark thus lies on a straight radial line between the center of the wheel and the lamp I94. Thereafter, the wheel is further turned slowly by hand, in the same direction, until the locating light again just comes on. This usually occurs when the wheel has been rotated one-half revolution from the position at which the mark on the tire was aligned with the locating light. The ring I 61 is of the same diameter as the housng Iilz, and the contact ItiI for the locating light is closable in response to very slight travel of the plunger. The outwardly offset part or the shifted ring I01 is in engagement with the plunger actuator blade I41 throughout a half revolution, and since even very slight eccentricity of the ring I E1! is sufiicient to cause illumination of the locating light in the manner described, the lamp remains illuminated during approximately one-half revolution, unless the ring has only been shifted to a very slightly eccentric position. Thus the angular positions corresponding to the points at which the outwardly onset part of the ring ends, correspond to the positions at which the locating light goes on and oil, and such positions also define the ends of a transverse diameter which is parallel to the axis about which the wheel is tilted in response to dynamic unbalance. It will also be observed (Fig. 5) that the switch mechanism carried in the casing I35 is arranged at to the longitudinal center line 230, previously referred to, connecting the locating lamp It"; with the center or the snar' t assembly, so that when the wheel is stopped with the tire mark at the opposite end of a diameter extending in the indicated direction parallel to the center line 230, the axis of tilt is actually located in a perpendicular direction, and extends through the shalt assembly at so to such center line, that is, parallel to the axis of the plunger assembly I40. lhe correctlng weights can accordingly beapplieu to the wheel at the ends of the marked diameter, that aeeasea is, one weight to the underside of the rim in radial alignment with the point marked on the tire, and the other Weight at the opposite side of the Wheel, 186 away, but on top of the rim.

Referring again to Fig. 3 and considering the relative positioning of the axis of the switch plunger Mill and the axis represented by the cabinet center line 238 previously referred to, it will be seen that the tire mark, applied in the manner indicated, will be located at the point of the wheel which was lowest during the dynamic balance test. Thus the correcting weight is applied to the underside of the rim in radial alignment with the mark on the tire and to the top of the rim 180 away. Preferably, the indicator light mechanism is so calibrated with relation to the average dimensions and mass of vehicle Wheels of the class to be tested that the amount of Weight denoted by indicating lights, in the manner previously described, should be applied to both sides of the rim in order to effect correction of the dynamic unbalance.

To assist in locating the axis of tilt in the manner described, a vertical center line or marking may be formed on the end of the cabinet in alignment with the axis 23%. In the shown construction, such vertical end marking may comprise a trim strip It will be appreciated that when the dynamic unbalance is slight, the shiitable ring it! may not be displaced suiliciently to cause the plunger to be actuated so that the positions at which the cating light goes on and oil" are exactly 180 apart. If this is the case, it will be found that after the tire is marked to indicate the position at which the locating li ht goes off, more than 180 of subsequent rotation will be required to cause the light to come on, so that the marked position of the tire will not then line-up with the rib 232 at the position where the light comes on. In this event, when the light does come on, the Wheel is stopped in the same manner, and the correcting weight is installed upon the underside of the rim at a position midway between the tire marking and the vertical rib 232. A like weight is thereafter installed on top of the rim 180 from the bottom weight.

While it will be apparent that the preferred embodiments of the invention herein disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning or" the subjoined claims.

What is claimed is:

1. Apparatus for checking the dynamic balance of motor vehicle wheels and the like, comprising in combination with a rotatable spindle, a wheel supporting quill drivably supported by, but rockable with respect to, said spindle, whereby during rotation of the quill, while the quill is carrying a dynamically unbalanced wheel, the wheel and quill may tilt about a transverse axis substantially perpendicular to a radial plane which extends through the center of the dynamically unbalanced mass, a camming portion carried by the quill, a laterally shiftable indicator actuator rotatably drivable by the spindle but slidable there- ,along to and from engagement with said camming portion, coasting camming portions carried by said actuator and engageable. with said firstrnentioned camming portion to shift said actuator laterally to a position corresponding to the position of said first-mentioned camming portion, gripping means for holding said actuator in a laterally shifted position to which it has been so 12 moved by said first-mentioned camming portion, and gaging means operatively connectable to said shiftable actuator.

2. Apparatus as defined in claim 1 wherein the spindle is rotatable on a substantially vertical axis and the quill is universally rockable on the spindle and includes a skirt portion spacedly below the point of rockable support of the quill and spacedly surrounding the spindle, said first-mentioned camming portion being carried by said skirt portion.

3. Apparatus as defined in claim 1 wherein the indicator actuator comprises a ring having an inclined cammin face engageable with said firstmentioned cainming portion, a generally cylindrical ring support of substantially the same external diameter as said ring, the ring and support being bodily slidable on the spindle and the ring being laterally shiftable with relation to the support, said gripping means being carried by said support.

4. Apparatus as defined in claim 1 wherein the spindle is rotatable on a substantially vertical axis and the quill is universally rockable on the spindle and includes a skirt portion spacedly below the point of rockable support of the quill and spacedly surrounding the spindle, said first mentioned camming portion being carried by said skirt portion, a support slidably keyed to the spindle and carrying the indicator actuator, said gripping means being carried by said support.

5. Apparatus as defined in claim 1 wherein the spindle is rotatable on a substantially vertical axis and the quill is universally rockable on the spindle and includes a. skirt portion spacedly below the point of rockable support or" the quill and spacedly surrounding the spindle, said first-ment1oned camming portion being carried by said skirt portion, a support slidably keyed to the spindle and carrying the indicator actuator, said gripping means being carried by said support, and means operatively connected to the support and to the gripping mean for moving the support along the spindle to carry the actuator to and from engagement with the skirt and to vary the effect of the gripping means.

6. Apparatus as defined in claim 1 wherein the spindle is rotatable on a substantially vertical axis and the quill is universally rockable on the spindle and includes a skirt portion spacedly below the point of rockable support of the quill and spacedly surrounding the spindle, said first-mentioned camming portion being carried by said skirt portion, a support slidably keyed to the spindle for axial movement therealon and carrying the indicator actuator, said actuator comprising a ring having a substantially fiat flange engaging and laterally shiftable with respect to the'support in a path transverse to the spindle axis but'bodily axially movable with the support, said gripping means being carried by said support and engageable with said flange.

7. Apparatus as defined in claim 1 wherein the spindle is rotatable on a substantially vertical axis and the quill is universally rockable on the spindle and includes a skirt portion spacedly below the point of rockable support of the quill and spacedly surrounding the spindle, said first-mentioned camming portion being carried by said skirt portion, a hollow cylindrical support slidably keyed to the spindle for axial movement therealong and carrying the indicator actuator, said actuator comprising a ring having a substantially flat flange engaging and laterally shiftable with respect to the support in a path transverse to the spindle axis but bodily axially movable with the support, said gripping means being carried by said support and engageable with said flange, and includin a flange-engagin friction element ex tending into the interior of said hollow cylindrical support, and spring means within the support reacting against friction element.

8. In a gaging device for determining conditions or" dynamic unbalance in rotatable bodies, in combination with a rotatable spindle, a wheel support carried and rotatably drivable by the spindle but universally rockable with respect thereto, an element carried by the spindle in circumscribing relationship thereto, said element b ing rotatable with said spindle and shiftable laterally with. respect thereto to positions of vary ing eccentricity with. relation to the of the spindle, said element being operatively connectiblc to and shiftable by the wheel support, and electrical contact means operable by said shiftable element, including a contact closable in response to slight eccentric shifting movement of said element and a plurality of contacts progressively closable in response to successively greater degrees of eccentricity of said element.

9. In a gauging device for determining conditions of dynamic unbalance in rotatable bodies, in combination with a rotatable spindle, a wheel support mounted upon and rotatably drivable by the spindle but universally rockable with respect thereto, an element separate from said wheel support mounted upon and rotatable with said spindle, said element being laterally shiitable at right angles to the axis of said spindle, means carried by said wheel support for laterally shifting said separate element in proportion to rocking of said support, and means for determining the extent of shifting movement of said element comprising a plunger engageable with said element, and a series of electrical contacts operable by said plunger.

10. In a gauging device for determining conditions of dynamic unbalance in rotatable bodies, in combination with a rotatable spindle, a wheel support mounted upon and rotatably drivable by the spindle but universally rockable with respect thereto, an element separate from said wheel support and mounted upon and encircling and rotatable with the spindle but shiftable laterally oi' the spindle to positions of varying eccentricities with relation to the axis of the spindle, means carried by said spindle for constraining movement of said element in a single plane only, said element being operatively connectible to and shiftable by the Wheel support.

11. In a gauging device for determining conditions of dynamic unbalance in 1:0 table bodies, in combination with a rotatable spindle, a wheel sup port mounted upon and rotatably drivable by the spindle but universally rockable with respect thereto, a rim mounted upon and encircling and rotatable with the spindle but shiitable laterally of the spindle to positions of varying eccentricity with relation to the axis of the spindle, said ring being separate from and shiftable by the wheel support, and gripping means carried by said spindle and frictionally bearing upon said ring for constraining movement of said ring at right angles to said spindle only and "for holding said ring in an eccentric position to which it may be so shifted.

12. In a gauging device for determining conditions of dynamic unbalance in rotatable bodies, in combination with a rotatable spindle, a wheel support carried and rotatably drivable by the spindle but universally rockable with respect thereto, an element encircling and rotatable with the spindle but slidable laterally to positions of varying eccentricity with relation to the axis of the spindle, means carried by said spindle for constraining movement of said element at right angles only to said spindle, said element being operatively connectible to and shiitable by the wheel support and electrical contact means operable by said shiftable element.

SIDNEY W. MARTIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,316,524 Martin Apr. 13, 1943 2,322,939 Inman June 29, 1943 2,378,018 Inman June 12, 1945 2,553,058 Martin May 15, 1951 

